Read and write the KHR_materials_unlit glTF/2.0 extension.

code/glTF2Asset.h

@@ -45,6 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * glTF Extensions Support:
  *   KHR_materials_pbrSpecularGlossiness full
+ *   KHR_materials_unlit full
  */
 #ifndef GLTF2ASSET_H_INC
 #define GLTF2ASSET_H_INC
@@ -741,6 +742,9 @@ namespace glTF2
         //extension: KHR_materials_pbrSpecularGlossiness
         Nullable<PbrSpecularGlossiness> pbrSpecularGlossiness;
 
+        //extension: KHR_materials_unlit 
+        bool unlit;
+
         Material() { SetDefaults(); }
         void Read(Value& obj, Asset& r);
         void SetDefaults();
@@ -1037,6 +1041,7 @@ namespace glTF2
         struct Extensions
         {
             bool KHR_materials_pbrSpecularGlossiness;
+            bool KHR_materials_unlit;
 
         } extensionsUsed;
 

code/glTF2Asset.inl

@@ -860,6 +860,8 @@ inline void Material::Read(Value& material, Asset& r)
                 this->pbrSpecularGlossiness = Nullable<PbrSpecularGlossiness>(pbrSG);
             }
         }
+
+        unlit = nullptr != FindObject(*extensions, "KHR_materials_unlit");
     }
 }
 
@@ -882,6 +884,7 @@ inline void Material::SetDefaults()
     alphaMode = "OPAQUE";
     alphaCutoff = 0.5;
     doubleSided = false;
+    unlit = false;
 }
 
 inline void PbrSpecularGlossiness::SetDefaults()
@@ -1253,6 +1256,7 @@ inline void Asset::ReadExtensionsUsed(Document& doc)
         if (exts.find(#EXT) != exts.end()) extensionsUsed.EXT = true;
 
     CHECK_EXT(KHR_materials_pbrSpecularGlossiness);
+    CHECK_EXT(KHR_materials_unlit);
 
     #undef CHECK_EXT
 }

code/glTF2AssetWriter.h

@@ -45,6 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * glTF Extensions Support:
  *   KHR_materials_pbrSpecularGlossiness: full
+ *   KHR_materials_unlit: full
  */
 #ifndef GLTF2ASSETWRITER_H_INC
 #define GLTF2ASSETWRITER_H_INC

code/glTF2AssetWriter.inl

@@ -343,6 +343,12 @@ namespace glTF2 {
             }
         }
 
+        if (m.unlit) {
+          Value unlit;
+          unlit.SetObject();
+          exts.AddMember("KHR_materials_unlit", unlit, w.mAl);
+        }
+
         if (!exts.ObjectEmpty()) {
             obj.AddMember("extensions", exts, w.mAl);
         }
@@ -683,6 +689,10 @@ namespace glTF2 {
             if (this->mAsset.extensionsUsed.KHR_materials_pbrSpecularGlossiness) {
                 exts.PushBack(StringRef("KHR_materials_pbrSpecularGlossiness"), mAl);
             }
+
+            if (this->mAsset.extensionsUsed.KHR_materials_unlit) {
+              exts.PushBack(StringRef("KHR_materials_unlit"), mAl);
+            }
         }
 
         if (!exts.Empty())

code/glTF2Exporter.cpp

@@ -526,6 +526,12 @@ void glTF2Exporter::ExportMaterials()
 
             m->pbrSpecularGlossiness = Nullable<PbrSpecularGlossiness>(pbrSG);
         }
+
+        bool unlit;
+        if (mat->Get(AI_MATKEY_GLTF_UNLIT, unlit) == AI_SUCCESS && unlit) {
+            mAsset->extensionsUsed.KHR_materials_unlit = true;
+            m->unlit = true;
+        }
     }
 }
 

code/glTF2Importer.cpp

@@ -281,6 +281,9 @@ static aiMaterial* ImportMaterial(std::vector<int>& embeddedTexIdxs, Asset& r, M
 
         SetMaterialTextureProperty(embeddedTexIdxs, r, pbrSG.specularGlossinessTexture, aimat, aiTextureType_SPECULAR);
     }
+    if (mat.unlit) {
+        aimat->AddProperty(&mat.unlit, 1, AI_MATKEY_GLTF_UNLIT);
+    }
 
     return aimat;
 }

include/assimp/pbrmaterial.h

@@ -56,6 +56,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define AI_MATKEY_GLTF_ALPHACUTOFF "$mat.gltf.alphaCutoff", 0, 0
 #define AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS "$mat.gltf.pbrSpecularGlossiness", 0, 0
 #define AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS_GLOSSINESS_FACTOR "$mat.gltf.pbrMetallicRoughness.glossinessFactor", 0, 0
+#define AI_MATKEY_GLTF_UNLIT "$mat.gltf.unlit", 0, 0
 
 #define _AI_MATKEY_GLTF_TEXTURE_TEXCOORD_BASE "$tex.file.texCoord"
 #define _AI_MATKEY_GLTF_MAPPINGNAME_BASE "$tex.mappingname"